We describe a system that enables us to perform exploratory empirical experiments with graph visualization techniques
by incorporating them into games that can be played on an internet site, the Graph Games Website
(http://www.cs.kent.ac.uk/projects/graphmotion/). We present a general discussion of games as a test-bed for empirical
experiments in graph comprehension, and explain why they might, in particular, provide a useful way to do exploratory
experiments. We then discuss the requirements for games that can be used and describe some individual games including
those we have tried on our own site.
The main part of the paper describes our own experiment in setting up a graph-gaming site where we have carried out
tests on the benefits of different graph visualizations. We discuss the design of the site, describe its underlying
architecture and present a promising initial trial on movement in graph visualization that gathered the results from over
70,000 played games. We then present some statistical conclusions that can be drawn from the resulting data. Finally, we
summarize the lessons that have been learned and discuss ideas for future work.